In the modern public switched telephone network (PSTN) and wireless telecommunication networks, an out-of-band common channel signaling (CCS) network is employed to facilitate the setup and tear down of voice and/or data communication sessions between telephone service subscribers. This signaling network is typically referred to as the signaling system 7 (SS7) network. The SS7 network utilizes a number of different signaling messages to perform call setup, call tear down, and database services. These signaling messages include ISDN user part (ISUP) messages for PSTN call setup and tear down, transaction capabilities application part (TCAP) messages for accessing database services, mobile application part (MAP) messages for providing mobile communications services, and signaling connection control part (SCCP) messages for carrying TCAP and MAP messages.
It is often the case within a signaling network that signaling messages require intermediate routing address translation prior to reaching their final destinations. The most common example of such intermediate routing address translation is referred to in the telecommunications industry as global title translation (GTT). GTT is defined in Telcordia Technologies Specification of Signalling System Number 7 Number, GR-246-CORE, Issue 07, Dec. 2, 2002 (hereinafter, “GR-246-CORE”), the disclosure of which is incorporated herein by reference in its entirety. As defined in GR-246-CORE, GTT provides network elements, such as wireline and wireless end office nodes (e.g., CLASS 5 switches, mobile switching centers, etc.), with the ability to send SCCP messages, such as SCCP messages carrying 800 number service queries, calling name (CNAM) delivery service queries, home location register (HLR) queries, short message service (SMS) messages, etc., into a signaling network without knowledge of the point code and subsystem number of the network entity that can provide the necessary service. In typical GTT processing, a global title address value is extracted from the SCCP called party address field of a message and is translated into a destination point code and subsystem number.
Within a signaling network, GTT processing may be performed by a service control point (SCP) or by a network routing node, such as a signal transfer point (STP) or Internet-protocol-capable signaling gateway (SG). Given the wide variety of services that may be concurrently supported by a signaling network, routing address translation data and applications may be separated according to service type. For example, one routing address translation application may translate HLR queries, while another routing address translation application may translate CNAM queries. Thus, one problem with performing routing address translations is determining which service or type of routing address translation processing is appropriate and where the appropriate routing address translation service can be obtained. Once again, routing address translation services may be provisioned on SCPs or STPs. In the former case, service selection may include identifying an SS7 point code and subsystem number associated with an SCP node that will perform the routing address translation. In the latter case, service selection may involve identifying a routing address translation data set and the logical or physical location of the translation data set within the network routing node.
In conventional service selection in ANSI networks, an SCCP parameter referred to as translation type (TT) is used to select the block of global title translation data associated with a particular service. For example, one translation type value may indicate a block of data for wireline number portably translations. Another translation type value may indicate the location of global title translation data for calling name translations. Yet another translation type may indicate the location of global title translation data for mobile communications services.
FIG. 1 illustrates an exemplary signaling network 100 where the TT is used to select a routing address translation service. In FIG. 1, signaling network 100 includes a mobile switching center (MSC) 102, an STP 104, a number portability (NP) SCP 106, a CNAM SCP 108, a pair of HLR SCP nodes 110 and 112, and an SMS Center (SMSC) SCP 114. In this example, it is assumed that STP 104 performs routing address translations and that STP 104 has separate blocks of routing address of translation data and/or separate applications to perform routing address translations for number portability service, CNAM service, HLR service, and SMS service.
In FIG. 1, a CNAM query message is originated by MSC 102 and routed to STP 104. STP 104 examines the TT parameter contained in the SCCP portion of the CNAM query message. Based on the TT, STP 104 selects a particular type or set of routing address translation data for use in translating the received signaling message. In this example, STP 104 selects the routing address translation data set for CNAM service. Once a routing address translation data set is selected, STP 104 uses global title address information contained in the message to perform a lookup in the CNAM routing address translation data set and extract the point code and subsystem number of CNAM SCP 108. The message is then routed to CNAM SCP 108 based on the extracted point code and subsystem number. CNAM SCP 108 may then provide calling name service for the query message.
In the network illustrated in FIG. 1, using the TT alone or in combination with other SCCP parameters to select a routing address translation service may work effectively provided that the operator of the network provisions the appropriate TT and other SCCP parameter values in STP 104. However, since some messages that arrive in network 100 may not originate from network 100, such messages may not have the same SCCP service selection parameter values used in network 100 because the service providers in the originating networks may use different SCCP parameter values to identify routing address translation services. In addition, some network operators may ignore one or more of the conventional SCCP parameter values used by other operators to indicate a routing address translation service type. Thus, service selection based solely on SCCP parameters fails to provide a universal service selection solution.
U.S. Pat. No. 6,577,723 discloses a system for using the TCAP protocol type, i.e., whether the message is ANSI TCAP or ITU TCAP, in order to determine how to process the SCCP portion of the message. The TCAP protocol type is determined by analyzing the first two bits in the TCAP portion of the message. Using the TCAP protocol type to control processing of an SCCP message allows SCCP messages that carry ANSI TCAP messages to be processed differently from SCCP messages that carry ITU TCAP messages. However, the TCAP protocol type does not indicate the application layer message type being carried by the TCAP message. In addition, ITU application layer messages can be carried by ANSI TCAP messages and ANSI application layer messages can be carried by ITU TCAP messages. Thus, selecting SCCP processing based on the TCAP protocol type fails to yield a universally applicable solution for service selection.
Accordingly, there exists a long felt need for improved methods and systems for universal, automatic service selection in a telecommunications signaling network.